From what I've tried to figure out, it doesn't seem like there's a way to change page permissions of member pages in order to allow access to members with certain roles only...
So I've thought maybe there's another way around it by just hiding the wix login button if a user has logged in whose role is not 'Artist'.
I used roles to change a users interaction and view of a page previously with the help of the forum here https://www.wix.com/corvid/forum/community-discussion/need-help-please-parsing-error-unexpected-token?origin=member_posts_page
I feel like perhaps there might be a way to do a similar thing on the Site code panel to hide the login button (and instead show a custom log out button) to users without the 'Artist' role.
Unless there is actually some easy way of changing member page permission that I haven't stumbled upon!